Cereal grains, processed grains, sand, minerals, and other bulk materials are stored within and moved among large bins, silos, tanks, buildings, ship holds, other large containers and on the ground. Dangers to humans handling these materials include asphyxiation due to avalanche, dust inhalation and explosions. Losses by the inaccurate shipping of the wrong quantities or components, and/or theft, and spoilage run into the billions of dollars worldwide. United States of America standard now call for +/−3% facility-wide accounting accuracy for volume measurement in commercial bulk storage bins. However, present methods of measurement can generally only accomplish +/−10% accuracy. OSHA (Occupational Safety and Health Administration) defined a grain silo as a confined space requiring detailed safety procedures, yet deaths still occur due to inaccurate or unavailable measurements of height and density of grain stockpiles.
The most common present day volume/height measurements generally use single point, manually measured plumb bob/tape measure methods and guesses as to surface contours or ultrasonic single point measurements. Occasional multi-point ultrasonic measurements of various heights are done, but the prohibitive costs of installing multi-thousand dollar sensors and their limited accuracy throughout a one hundred foot wide storage bin impede wide use of this known technology.
Cost effective, timely, and accurate material management is crucial to the economic viability of storage and transfer facilities. A method for eliminating the waste and inaccuracy inherent in current labor-intensive methods of measuring bulk material quantity is needed. The present invention is a state-of-the art improvement due to its ability to profile an entire surface/volume in three dimensions instead of just at a point. Furthermore, the same invention can be used to not only measure a static volume but also a dynamic volume (one that is changing). Finally, the present invention can be packaged for use in hazardous (explosive) locations, non-hazardous locations, damp or wet locations, and other exposures.
For grain, good management is crucial to preserve grain quality. To maintain grain in good quality, its condition must be constantly monitored for numerous reasons including preventing the grain from going bad and to prevent an isolated condition problem from spreading throughout the grain volume. For grain, moisture content (MC) management is also crucial. MC is a major factor in deciding when to move grain out to market or how to blend several grain loads to achieve a marketable, homogeneous commodity. MC is also used to determine whether or not-the grain needs artificial drying. Moisture content knowledge is also used to automate interlocked control of other plant equipment such as aeration fans, etc. Insect infestation, mold, bacteria, moisture, improper temperature control, rain and/or condensation all contribute to spoilage if not properly managed. This invention provides early detection and warning to storage facility operators.
In the handling and storage of bulk grains and other bulk materials, the substance(s) may be misidentified or misdirected to an incorrect storage facility. Usually this is a result of human error. Accidental mixing results in a significant expense to the grain or material handler, either in the cost of sorting the grain/material (if possible), or in the loss of value of the mixed product. Similarly, during audits of such facilities the grain or bulk material must be properly identified so that proper value may be assigned to each grain/material stored.
Quantity (volume) has been previously calculated via a manual process. A person typically travels to the material container and makes a single point measurement of distance from the container inspection port to the material surface. This is done by use of a tape measure and plumb bob, an ultrasonic transducer, or a handheld laser rangefinder. A visual estimate is then made of the shape at other points along the surface. Finally volume is calculated using a shape estimate and the single distance measurement.
Currently, personnel manually identify incoming bulk grain or other material and route the grain to a storage facility based on that identification. Correctness of the proper routing is based on their memory of where material is stored. There are no machine vision recognition systems to verify or cross check the human decisions. Also, some types of grain/material look very similar to others, such as different varieties of the same type of grain. These may thus be easily misidentified, adding to the human error potential. Another related source of error is the manual entry of material information into computer databases to track material location and movements. Errors in data entry often lead to the misdirection of material within a handling facility.
There are currently no real-time in-flow sampling systems on the market for constituent evaluation and quality grading. Grain recognition and condition monitoring are typically performed by entering a storage bin and using human vision, smell, and tactile feedback from “walking the grain”.
Linear arrays of temperature sensors (temperature cables) have proliferated throughout the grain storage industry to assist in condition monitoring. Heat generated in the grain fermentation process builds up in the grain pile and is eventually detected via a temperature cable passing near or through the region of spoilage. The excellent thermal-insulating properties of bulk grain severely constrain the effective spoilage detection of a single temperature cable. As a result, condition monitoring of 100% of a container's grain volume via temperature cables is cost prohibitive, as it requires an enormous number of closely spaced cables. As well, a cable generated alarm is usually too late for spoilage prevention and only allows the user to prevent further excessive spoilage.
It is also common practice to use database accounting to track some of the above characteristics (volume and material type). No processes use machine vision systems that are sufficiently sophisticated and accurate enough to generate or validate the data because the enabling technology has not been available.
There currently is no manual or technological method for monitoring the moisture content or density of bulk stored grains or other bulk commodities.
For grain and some other bulk materials, a given volume is not homogeneous. Therefore, sampling and sorting are required to characterize the bulk content for value (possible discounting) and segregation. This quality sampling/management function is widely known and utilized on small samples. The small samples are taken as a statistical representation of the total bulk load. Statistical sampling is used because no continuous flow analysis (thus total bulk load) enabling technology exists.
Managing bulk contents (measuring it, verifying what type it is, checking its condition, etc.) or doing maintenance on the storage container can be dangerous. It is dangerous because personnel are often required to enter the storage tank to perform those management functions. Bin entry exposes personnel to dangers of asphyxiation, poisoning, as well as accidental burial in the bulk material due to unstable subsurface conditions and/or conditions due to loading or unloading the tank. Workers “walk the grain” and can be buried in the grain due to inaccurate depth estimates. Each year, numerous people are killed or injured in this manner. Consequently, personnel entry into nearly all bulk storage containers is regulated by OSHA under confined space rules.
Accurate quantity determination and safe personnel contact with the commodity are also dependent on knowing the density of the bulk. This includes both knowing the stratification of density and localized density irregularities. The present invention teaches many instrument types and methods to gather the density information.
The following is a summary of the deficiencies of the current art:
1. Volume Measurement
The chief deficiency in current methods of measuring quantity (volume) of stored powders and bulk materials is the failure to gather enough data for fine resolution of the stored pile's surface shape. Surface shape translates into volume. Thus, the more inaccurate the surface measurements the more inaccurate the calculated volume.
As material is loaded into or withdrawn from a storage container, the surface shape of the stored mass will change significantly. Since accurate volume knowledge is important to a storage facility's business goals of inventory accounting and regulatory compliance, common practice is to measure volume frequently. Most volume measurements are carried out using, as a basis for the calculation, the vertical distance from a reference point near the roof of a storage container to a single point on the material surface. An estimate is then made of the surface shape using human visual judgment or knowledge of the bin's recent fill/discharge history or a combination of both, and volume is calculated. Depending on the ratio of material volume to available container volume as well as on the container's aspect ratio (height to diameter or width), errors in surface shape assumptions can lead to volume miscalculations in excess of 10%. Error is minimal for tall, narrow bins since small bin diameter keeps all possible surface shape dependent volume variations small relative to the actual volume of the container's contents. Errors due to lack of material surface knowledge are largest for bins with aspect ratios nearer to unity. Error magnitude also has a strong dependence on the surface single-point location. A measurement made at the bin periphery will lack information about the height (load-in) or depth (discharge) of the central area which may be a conical shape. In contrast, a measurement made near the center of the pile surface may generally provide accurate knowledge of the cone height/depth, but it cannot provide an adequate picture of the complex surface profiles from center to perimeter that often result from repeated cycles of partial load-in and partial discharge. From a life-cycle cost standpoint, manual methods are very labor intensive, pose a potential safety risk to personnel trying to obtain the manual measurements, and can lead to large errors. For automated state-of-the-art systems like ultrasonic transducers suspended from the ceiling, the cost can be fairly expensive without significant accuracy improvement over a manual system. For instance a currently available ultrasonic system with 10 transducers measures only 10 points of information for a material cost ranging between 10-15 thousand dollars.
2. Volume Discharge, Structural Monitoring, & Live Video
There are no known bulk level detection systems that can also accurately determine tank discharge rates, monitor the structural integrity of the bulk tank, and provide live video all in one instrument.
3. Recognition
The primary deficiency in current bulk material type recognition and tracking techniques is the reliance on human operator input for critical inventory management information on type identification during load-in and retrieval operations. Human errors in identification, logging, and record management of material type, incoming inventory destinations, and existing inventory storage locations lead to costly, inadvertent material mixing incidents. When inadvertent mixing occurs in the grain handling industry, the remedy choice is to either sell the mixture as feed at 50% or less of market value or to separate it with separation equipment. Separators cost many thousands of dollars and require significant labor.
4. Condition Monitoring
The major deficiencies in the area of bulk material condition monitoring and tracking, especially organic materials such as cereal grains, is the reliance on relatively insensitive temperature cable technology and inspection via human olfactory and tactile sensing. Linear arrays of thermal sensors are arranged within long cables that are typically hung vertically from the roof of a storage bin such that, when material is loaded in, the cables pierce the pile at regularly spaced grid points across the surface. Since most bulk materials, including cereal grains, possess excellent thermal insulating properties, this method of condition monitoring detects only high rate exothermic condition loss reactions (e.g., fermentation during spoilage). The reaction heat is detectable only inasmuch as the zone of reaction is within the region of influence of a nearby temperature sensing cable. This often leads to situations where condition loss is well underway and has propagated through an economically significant portion of the stored material pile before detection by temperature cables is possible.
Human inspection is frequently employed to detect or verify condition loss problems, but this method requires a visit to the bin in question and, at a minimum, opening an inspection port for a sniffing test by the inspector to determine the presence of any telltale off-odors. Once detected, either by temperature cables or by human sniffing, the extent and recoverability of the condition loss problem is usually assessed via personnel “walking the grain” for tactile, visual and further olfactory information on the problem.
A typical temperature cable system cost is between 3-10 thousand dollars per bin depending on the number of cables employed.
5. Safety Hazards Awareness
The chief deficiencies in the area of safety hazards awareness are a lack of automation in routine inventory management tasks and a lack of up-to-the-minute information on important storage bin variables related to personnel safety. Manual verification of bin contents, manual inspection of bin content condition, and manual volume measurements all require storage facility personnel to perform potentially hazardous actions related to accessing the stored material, namely bin climbing and bin entry. If bin entry is required for troubleshooting, no current information is available to the entering personnel on vital factors such as material depth across the entire surface and environmental factors such as interior temperature and atmospheric constituents.
What is needed is an automated and integrated system of instrumentation for:    1.) accurately determining and tracking material volume by fully scanning a surface,    2.) recognizing material contents,    3.) monitoring material conditions,    4.) monitoring material physical properties,    5.) sampling and evaluating material constituents and quality during flow    6.) monitoring storage environmental conditions and    7.) providing safety data and awareness related to bulk materials storage within large bins, buildings, or other large containers.    8.) providing live in-bin video.
The present invention provides the above mentioned needs.
The present invention provides whole-surface measurement accuracy by providing +/−one inch accuracy over the entire surface of a pile of stored grain instead of measuring just one point, on a real time basis as the volume is changing during loading and unloading of the storage container. On-the-fly sampling of loading materials can measure and provide data such as moisture content, oil content, type of grain, contamination, and dust hazards. Cross checking of total grain flow during loading against a measured stored volume is achievable for the first time.
The present invention provides, automated, on-demand measurement of bulk material volume, recognition of material (e.g., grain species and variety), sampling measurement of flowing bulk material for other quality parameters (e.g. grain shapes for cross validation and count of whole versus damaged grains, foreign material, insect damage/presence, mold or heat damage, and constituent content such as moisture, protein, oil, starch, etc. The present invention will allow for total tank/silo monitoring and total bulk sampling/measuring of the flow into or from the storage tank/silo. It also monitors levels of condition degradation via sampling of by-product gases. It also improves life safety awareness. All of the above are implemented in the grain flow to, from, or within large storage and holding containers and on large ground piles.
The present invention is continuously operable as dust levels allow, but not during container load-in for optical instruments. This is also true for all other non-optical, non-contact instruments such as ultrasonic or radar-based instruments. Alternate embodiments teach instruments in a portable form having semi-continuous operation.
Since existing art in volume measurement employs single point distance measurements and visual estimation of material surface shape, volume errors can be large due to weakness in the accuracy of the surface shape estimate. The present invention increases volume measurement accuracy by using a surface profiling technique. Actual surface shape and height are thereby obtained, eliminating reliance on visual estimates. Human presence at the container is not required.
The present invention monitoring system is fully automatic, allowing a user to remotely monitor conditions within a storage bin. It is much more convenient and safe than traditional methods that require people to enter the storage bin. It provides a more accurate measurement of volume and can be used more frequently than traditional methods. It also can provide earlier detection of content degradation. The present invention also helps prevent inadvertent mixing of different types of bulk materials. Finally, the present invention provides critical safety related data to storage facility personnel when entering the storage bin is deemed necessary.
A Feature Summary Includes:
The present invention provides automation that eliminates the labor-intensive practice of visiting each storage container each time volume of contents must be measured or suspicious grain conditions must be investigated.
The present invention provides generation of a surface height profile that markedly increases accuracy of volume measurement over the current dominant method involving a single-point distance measurement and estimate of the pile's surface shape.
The present invention provides continuous whole-volume monitoring of moisture content and density variations that provide much earlier warning of deteriorating grain condition and provide a never-before-available ability to locate dangerous voids that may develop in the grain pile.
The present invention provides quick-response detection that is not dependent on large heat output from an exothermic reaction or other heat generating degradation sources. This detection is independent of grain insulating properties, which currently hamper detection via a temperature cable system. As well, it will replace the necessity of air monitoring for human presence in a confined space.
The present invention can be used for produce (vegetables) storage inland and/or during shipping, and also for coal/fossil fuel storage and shipping, wherein fuels are subject to state changes during storage. It can also apply to inorganic materials inventory accounting for high value products such as grit for architectural tiles and the like.
The present invention will give total surface measurement (as many points as desired) for less cost than the above stated ultrasonic system. Consequently, the single point systems, due to their inability to catch volume problems (i.e. theft), cost the user significant amounts of money where the present invention will prevent any problems of this nature from going undetected.
The present invention will render tank discharge rates along with tank structural monitoring and live video. Furthermore, these features are included in the base system cost.
The cost of the present invention system is significantly less than separators, which are required due to inadvertent mixing and will prevent these accidents.
The present invention will give earlier detection than temperature cables by monitoring any out-gassing while costing significantly less.